Methods of forming fully embedded bumpless build-up layer packages and structures formed thereby

ABSTRACT

Methods of forming a microelectronic packaging structure and associated structures formed thereby are described. Those methods may include a die embedded in a coreless substrate, wherein a mold compound surrounds the die, and wherein the die comprises TSV connections on a first side and C4 pads on a second side of the die, a dielectric material on a first side and on a second side of the mold compound; and interconnect structures coupled to the C4 pads and to the TSV pads. Embodiments further include forming packaging structures wherein multiple dies are fully embedded within a BBUL package without PoP lands.

RELATED APPLICATION

The present application is a Divisional of U.S. application Ser. No.12/890,045 filed Sep. 24, 2010, entitled “METHODS OF FORMING FULLYEMBEDDED BUMPLESS BUILD-UP LAYER PACKAGES AND STRUCTURES FORMEDTHEREBY”.

BACKGROUND OF THE INVENTION

As semiconductor technology advances for higher processor performance,advances in packaging architectures may include coreless bumplessbuild-up Layer (BBUL-C) package architectures and other such assemblies.Current process flows for BBUL-C packages involve building of thesubstrate on a temporary core/carrier capped with copper foil, which isetched off after the package is separated from the core.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming certain embodiments of the present invention,the advantages of this invention can be more readily ascertained fromthe following description of the invention when read in conjunction withthe accompanying drawings in which:

FIGS. 1 a-1 g represent methods of forming structures according to anembodiment of the present invention.

FIGS. 2 a-2 j represent methods of forming structures according to anembodiment of the present invention.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

In the following detailed description, reference is made to theaccompanying drawings that show, by way of illustration, specificembodiments in which the methods may be practiced. These embodiments aredescribed in sufficient detail to enable those skilled in the art topractice the embodiments. It is to be understood that the variousembodiments, although different, are not necessarily mutually exclusive.For example, a particular feature, structure, or characteristicdescribed herein, in connection with one embodiment, may be implementedwithin other embodiments without departing from the spirit and scope ofthe embodiments. In addition, it is to be understood that the locationor arrangement of individual elements within each disclosed embodimentmay be modified without departing from the spirit and scope of theembodiments. The following detailed description is, therefore, not to betaken in a limiting sense, and the scope of the embodiments is definedonly by the appended claims, appropriately interpreted, along with thefull range of equivalents to which the claims are entitled. In thedrawings, like numerals refer to the same or similar functionalitythroughout the several views.

Methods and associated structures of forming and utilizingmicroelectronic packaging structures, such as fully embedded corelessBBUL package structures, are described. Those methods may includeforming a die embedded in a coreless substrate, wherein a mold compoundsurrounds the die, and wherein the die comprises TSV connections on afirst side and C4 pads on a second side of the die, wherein a dielectricmaterial is disposed on a first side and on a second side of the moldcompound, and wherein interconnect structures are coupled to the C4 padsand to the TSV pads through the dielectric material on both sides of thedie. Methods of the embodiments enable the formation of dual sided,fully embedded packages using bumpless build-up layer (BBUL) technology.

Methods and associated structures of the embodiments further includeforming a first die embedded in a coreless substrate, a first dielectricmaterial adjacent the first die, and a second die embedded in thecoreless substrate, wherein the second die is disposed above the firstdie and a second dielectric material is adjacent the second die.Interconnect structures further connect the first die to solderconnections on an outer portion of the coreless substrate, wherein thecoreless substrate does not comprise PoP (package on package) lands tocouple the second die to the coreless package. The methods of theembodiments further enable the formation of a package structure whereinthe overall package is made completely by the BBUL process rather thanby a hybrid process involving a BBUL package process and a BGA/wire bondpackaging process.

FIGS. 1 a-1 g illustrate embodiments of methods of formingmicroelectronic structures, such as package structures, for example.FIG. 1 a illustrates a carrier material 100. In one embodiment, thecarrier material 100 may comprise a multi-layer copper foil that mayserve as a temporary carrier, such as a microelectronic die carrier 100.In other embodiments, the carrier material 100 may comprise any suitableconductive carrier material 100. In an embodiment, the carrier material100 may optionally comprise an adhesive layer 102.

In an embodiment, a die 106 may be placed on the carrier material 100,which may in an embodiment comprise a temporary die carrier 100. The die106 may comprise controlled collapse chip connections (C4) pads 104 andthough silicon via (TSV) pads 105. In an embodiment, the C4 pads may bedisposed on a first side 103 of the die 106, and the TSV pads may bedisposed on a second side 101 of the die 106. The die 106 may be placedC4 side up, or in other embodiments may be placed TSV pad 105 side up onthe die carrier 100. In an embodiment, the adhesive 102 can be dispensedeither on the die 106 or on the carrier 100. In some cases, the 102adhesive film and/or an attach process may be used to attach the die 106to the temporary carrier 100.

In an embodiment, a mold compound 108 may be applied to surround/embedthe die 106 (FIG. 1 b). In an embodiment, the mold compound 108 may bedispensed and cured to over-mold the die 106. The mold compound 108 maybe applied such that the die 106 is completely embedded in the moldcompound 108. A portion of the mold compound 108 may then be removed toexpose the C4 pads 104 and TSV 105 pads (FIG. 1 c). In an embodiment,back-grinding of the mold compound 108 may be performed to expose the C4pads 104 and TSV pads 105, and the temporary carrier 100 may be removedfrom the die 106 during back-grinding removal process. In an embodiment,the die 106 may remain entirely embedded in the mold compound 108 afterexposure of the C4 and TSV pads 104,105. The mold compound 108 may serveas a base for subsequently formed build-up layers of a microelectronicpackage structure formed according to embodiments herein, and mayfurther serve to reduce warpage during subsequent processing of such apackage structure. The remaining mold compound 108 may comprise a firstsurface 107 and a second surface 109.

Dielectric material 110, 110′ may be formed on the first surface 107 andon the second surface 109 of the mold compound 108 that surrounds thedie 106 (FIG. 1 d). In an embodiment, the dielectric material 110, 110′may be formed/attached by a laminating process, for example. Thedielectric material 110, 110′ may provide a level plane for a subsequentbuild-up process.

In an embodiment, vias 112 may be formed in the dielectric material 110on the first surface 107 of the molding compound 108, to connect to theC4 pads 104 of the die 106, and vias 112′ may also be formed in thedielectric material 110′ on the second surface 109 of the moldingcompound 108 to connect to the TSV pads 105 of the die 106. The vias112, 112′ may subsequently be filled with conductive material 113 (FIG.1 e). In an embodiment, a semi-additive process (SAP) may be used toform interconnect structures 114 (which may comprise first metal layers,for example) to connectively couple to the C4 pads 104 on the die 106,and interconnect structures 114′ may also be formed to connectivelycouple to the TSV pads 105 of the die 106. In an embodiment, theinterconnect structures 114 may be disposed on the first surface 107 ofthe molding compound 108 and may be connected to the C4 pads 104 by theconductive vias 113. The interconnect structures 114′ may be disposed onthe second surface 109 of the molding compound 108 and may be connectedto the TSV pads 105 by the conductive vias 113′.

Subsequent layers may then be formed using SAP build-up processing, forexample, wherein further dielectric layers, such as dielectric layers110″, 110′″, conductive vias 113″, 113′″ and interconnect structures114″, 114′″ may be formed upon each other according to the particulardesign requirements, to form a coreless package structure 120 byutilizing the buildup process (FIG. 1 f). In an embodiment, the corelesspackage structure 120 may comprise a BBUL coreless package structure120, and the die 106 may be fully embedded in the coreless packagestructure 120.

In an embodiment, the coreless package structure 120 may comprise adual-sided package 120 on both sides of the die 106, which is embeddedin mold compound 108.

In an embodiment solder resist 116, 116′ may be used to form openings118, 118′ to connectively couple to the C4 and/or the TSV pads 104, 105on the outermost layer of the package structure 120. In an embodiment,solder resist can be used to open up the pads on the outermost layer ofthe package structure 120. In an embodiment, solder balls 122 may beformed in the openings 118′ (and/or 118) to couple to the die 106. (FIG.1 g). In an embodiment, the solder balls 122 may comprise ball girdarray (BGA) balls 122, that may be attached to the package structure120. In an embodiment, a additional dies and/or packages 124 may beattached/coupled through the openings 118 (and/or 118′, referring backto FIG. 1 g) to an outer portion of the coreless package structure 120.In another embodiment, through mold-vias (not shown) may be formedthrough the dielectric layers to increase power supply to the corelesspackage structure 120, for example.

Thus, methods of fabricating dual sided fully embedded packagestructures using BBUL technology are enabled. The coreless packagestructure 120 may be utilized in stacked die/package applications.Embodiments provide stiffer package structures owing to the presence ofthe mold compound, and enable a fully embedded die solution, thusreducing the package Z-height. The embodiments further facilitate theintegration of TSVs for stacked package applications, while improvingwarpage, while providing for simultaneous processing of a base packageand stacked package(s). The embodiments enable packaging, assembly,and/or test solutions for graphics, wireless CPU's/processors, ChipsetsMulti-Chip/3D package structures/systems, including CPU's in combinationwith other devices such as Memory (e.g., flash/DRAM/SRAM/etc) and boardssuch as motherboards, for example.

FIGS. 2 a-2 j illustrate embodiments of methods of formingmicroelectronic structures, such as BBUL package structures, forexample. FIG. 2 a illustrates a carrier material 200. In one embodiment,the carrier material 200 may comprise a multi-layer copper foil that mayserve as a carrier, such as a microelectronic die carrier. In otherembodiments, the carrier material 200 may comprise any suitableconductive carrier material 200. In an embodiment, the carrier material200 may comprise an adhesive layer 202, such as a die back side film(DBF) that may be pre-attached to a first side 201 of the carrier 200and a second side of the carrier 203.

A first die 206, such as a first memory die 206 for example, may bemounted/attached on the first side 201 of the carrier 200 using thepre-attached DBF 202, for example. A second die, such as a second memorydie 206′, may be attached on the second side 203 of the carrier 200using the pre-attached DBF 202, for example. The first and second die206, 206′ may comprise conductive structures 204, 204′, respectivelywhich may comprise C4 interconnect structures 204, 204′, for example. Adielectric material 210 may be placed/laminated on the first side 201 ofthe carrier 200 (FIG. 2 b). A dielectric material 210′ may beplaced/laminated on the second side of the carrier 203 such that thefirst die 206 and the second die 206′ are fully embedded within thedielectric materials 210, 210′ respectively. In an embodiment, the firstmemory die 206 may serve to be the first embedded die 206 in a BBULprocess.

Vias 212, 212′ may be formed through the dielectric material 210, 210′,by UV/CO2 laser, for example, to expose the conductive structures 204,204′ on the die 206, 206′ respectively (FIG. 2 c).

The vias 212, 212′ may subsequently be filled with conductive material213, 213′ (FIG. 2 d). In an embodiment, a semi-additive process (SAP)may be used to form interconnect structures 214 (which may comprise afirst metal layer, for example) to connectively couple to the C4 pads204 on the first die 206.

Interconnect structures 214′ may also be formed to connectively coupleto the C4 pads 204′ of the second die 206′. In an embodiment, theinterconnect structures 214 may be disposed on/over the dielectricmaterial 210 and on/over the first die 206, and may be coupled to the C4pads 204 by the conductive vias 213. The interconnect structures 214′may be disposed on/over the dielectric material 210′ and on/over thesecond die 206′, and may be connected to the C4 pads 204′ by theconductive vias 213′.

Subsequent layers may then be formed using a SAP build-up processing,for example, wherein further dielectric material 210″, 210′″, conductivevias 213″, 213′″ and interconnect structures 214″, 214′″ may be formedupon each other according to the design requirements of the particularapplication, by utilizing a SAP buildup process (FIG. 2 e). In anembodiment, a third die 216, such as a CPU die 216 may bemounted/attached above the first die 206, on/above the first surface 201of the carrier 200. A fourth die 216′, which may comprise a CPU die, forexample, may be attached/mounted above the second die 206′ (FIG. 2 f).Additional dielectric material 211, 211′ may be formed surrounding thethird die 216, and the fourth die 216′ respectively. Subsequent layersmay then be formed using SAP build-up processing, for example, whereinadditional conductive vias 213″, 213′″ and interconnect structures 214′,214′″ may be formed upon each other according to the particular designrequirements (FIG. 2 g). In an embodiment, further vias andmetallization layers may be formed on the third and fourth dies 216,216′, according to the particular application, wherein greater than twolevels of metallization may be formed utilizing the SAP build-upprocess.

In an embodiment, solder resist 216, 216′ can be used/patterned on/abovethe third and fourth die 216, 216′ to open up pads 215, 215′ (FIG. 2 h).In an embodiment, the first die 206 and the third die 216 may beseparated from the second die 206′ and the fourth die 216′ along thetemporary carrier 200 to form a first package structure 220 and a secondpackage structure 220′. In an embodiment, the first and third die 206,216 may comprise a first BBUL package structure 220 without package onpackage (PoP) lands after separation from the carrier 200. In anembodiment, the second and fourth die 206′, 216′ may comprise another,second BBUL package 220′ without PoP lands after separation from thecarrier 200.

In an embodiment, solder balls 222 may be formed on the pads 215 tocouple to the die 206, 216 of the first package 220 (FIG. 2 i). Solderballs 222′ may be formed on the pads 215′ to couple to the die 206′,216′ on the second package (not shown). In an embodiment, the solderballs 222 may comprise ball gird array (BGA) balls 222 that may beattached to the package structure 220. Thus, the BBUL package structure220, wherein there are no PoP lands, may comprise a BBUL corelesspackage structure 220, and the first and second die 206, 206′ may befully embedded in the coreless BBUL package structure 220.

In an embodiment, additional die, such as a fifth 221 and a sixth die221′, for example, may be formed adjacent to the first die 206 in thefirst package 220 and the third die 206′ in the second package 220′ (notshown) respectively (FIG. 2 j, depicting first package 220). In anembodiment, the fifth die 221 may be disposed in the dielectric material210 on the first side of the carrier 200 and the sixth die 221′ may bedisposed in the dielectric material 210′ on the second side of thecarrier 200 of the second package 220′ (not shown).

Thus, embodiments included herein comprise BBUL processes and structureswherein multiple dies are fully embedded within the BBUL package. In anembodiment, the top die, such as a top memory die, may be the firstembedded die in the BBUL process of the embodiments herein. Benefits ofthe embodiments herein include overall cost of processing reduction ofthe final package, due to the removal of the PoP substrate and a CAMstep (such as a memory die attach to PoP package, for example). Theoverall Z height of the final ‘pure’, non-PoP land comprising BBULpackage may be reduced. PoP package solder joint reliability issues(which may be due to lack of anchoring of the copper PoP pad), may beeliminated. Furthermore, with the embedded stacked die, the BBUL packagestructures of the various embodiments herein reduce warpage, thusimproving the yield during surface mount to a motherboard. The overallpackage of the various embodiments herein are made completely by theBBUL process alone, rather than by a hybrid process comprising acombination of BBUL package processing and BGA/wire bond packageprocessing as in prior art processes/structures.

Prior art BBUL packages may in fact comprise a combination of a BBULpackage and a PoP package, wherein the PoP package is surface mountedonto the BBUL. That is, only the lower package in the prior art is aBBUL process/package and the top PoP package is a non-BBUL package, thetop die in the PoP portion not being fully embedded in the BBUL package.The embodiments herein eliminate the PoP package completely. The variousembodiments enable packaging, assembly, and/or test solutions forCPU's/processors, chipsets multi-chip/3D packages including CPU incombination with other devices, memory (e.g., flash, DRAM/, RAM/etc.),boards (e.g., motherboards, etc.).

Although the foregoing description has specified certain steps andmaterials that may be used in the method of the present invention, thoseskilled in the art will appreciate that many modifications andsubstitutions may be made. Accordingly, it is intended that all suchmodifications, alterations, substitutions and additions be considered tofall within the spirit and scope of the invention as defined by theappended claims. In addition, it is appreciated that variousmicroelectronic structures, such as package structures, are well knownin the art. Therefore, the Figures provided herein illustrate onlyportions of an exemplary microelectronic device that pertains to thepractice of the present invention. Thus the present invention is notlimited to the structures described herein.

1. A method comprising; attaching a first die to a first side of acarrier; attaching a second die to a second side of the carrier; formingdielectric material on the first side of the carrier and formingdielectric material on the second side of the carrier; forming viaconnections and interconnect structures through the dielectric materialon the first side of the carrier to connect to the first die and formingvia connections and interconnect structures through the dielectricmaterial on the second side to connect to the second die; attaching athird die on the dielectric material on the first side of the carrierand attaching a fourth die on the dielectric material on the second sideof the carrier; forming additional dielectric material and interconnectstructures on the third die and forming additional dielectric materialand interconnect structures on the fourth die; and separating the firstand third die from the second and fourth die along the carrier to formtwo separate package structures.
 2. The method of claim 1 furthercomprising wherein the first and third die are fully embedded in a firstpackage, and wherein the second and fourth die are fully embedded in asecond package
 3. The method of claim 2 further comprising wherein thefirst and second packages do not comprise a PoP lands.
 4. The method ofclaim 1 further comprising wherein the first and second die comprise amemory die.
 5. The method of claim 1 further comprising wherein thefirst and second die comprise a CPU die.
 6. The method of claim 4further comprising attaching a fifth die adjacent the third die on thedielectric material on the first side of the carrier and attaching asixth die adjacent the fourth die on the dielectric material on thesecond side of the carrier.
 7. The method of claim 1 further comprisingwherein the carrier material comprises copper.
 8. The method of claim 1further comprising wherein each of the two packages comprise coreless,bumpless, build up layer packages.
 9. A method of forming a packagestructure comprising; attaching a die to a carrier material; forming amold compound over the die; removing a portion of the mold to exposepads on a first side and on a second side of the die; forming dielectricmaterial on first and second surfaces of the mold compound; forming acoreless substrate by building up layers on the dielectric materialdisposed on the first and second surfaces of the mold compound.
 10. Themethod of claim 9 further comprising: forming vias and interconnects toconnect to the pads on the first and second sides of the die.
 11. Themethod of claim 9 further comprising wherein the structure comprises adual sided package, wherein the die is fully embedded in the dual sidedpackage.
 12. The method of claim 9 wherein the structure comprises aportion of a coreless, bumpless, build up layer package, and wherein asecond die is attached to the package.
 13. The method of claim 10further comprising wherein the die comprises TSV pads on a first sideand C4 pads on a second side of the die.